I think the term 'fear of vaccuum' is just a picturesque way of describing a tendency towards clutter; there is no implication of a psychological 'theory' or the existence of an actual fear. One should not read literal meanings into turns of phrase.As for rejection of 'tribe' as a useful classification concept, I think we are going overboard here (deconstructionism is fashionable these days!). After all, we instantly recognize a Tekke or Yomud 95% of the time. If the distinctions between tribes that have settled in close proximity to each other become blurred, that is no reason to toss out the concept entirely.